This invention relates to a material for destroying concrete structure and the like. More particularly, the invention relates to a material of the kind which is injected into a bore or cavity formed in a concrete structure or other body which is to be destroyed.
It has been conventional practice to disintegrate of fragment concrete structures by a method which relies upon an externally applied mechanical impact, or by a method based on the use of gunpowder. However, these methods raise problems in terms of public hazards and health as they involve great vibration and noise and pose a high level of danger for workers in the area. Thus there has been demand for the development of a novel method of destruction which is both safe and simple to carry out.
Several chemical methods of destruction have been proposed in recent years in an effort to meet such demand. According to these methods, concrete structures or the like are destroyed by boring a hole in the structure, sealing quicklime and water in the hole to induce a hydration reaction which gives rise to an approximate two-fold increase in volume, and utilizing this volumetric expansion force to fragment or destroy the structure. Since the quicklime does not harden upon hydration, quicklime which is merely poured into the bored hole and then hydrated overflows from the mouth of the hole upon hydration and expansion, so that an effective expansive pressure does not act upon the structure, thereby making complete destruction impossible. These previous proposals therefore require means for transferring the expansive pressure to the structure in an effective manner. For example, a metal cap or the like is used to seal the hole to form a rigid cavity in which the quicklime is then hydrated. This allows the resulting volumetric expansion force to act upon the structure with a greater effectiveness.
These previous proposals teach a variety of means for effecting the mechanical seal, but all of them are defective in that they require considerable time to perform the necessary labor. Moveover, since it is necessary to bore a large number of holes in a concrete structure in order to destroy it, the aforesaid conventional methods of destruction are inefficient. For these reasons such methods have not as yet come into common use.
Nevertheless, there is much to be said in favor of the chemical methods of destruction in terms of their social value, namely that they are simple, safe and inexpensive. This is because they utilize low-cost quicklime which need only be mixed with water and then injected into a bored hole to destroy a concrete structure or base rock. The value of such methods would be enhanced even further, however, if it were possible to dispense with the mechanical sealing means.